I wonder how culture specific this is. I once read a fascinating article about the differences in taste between Quebec and French women, where the former preferred muscular men while the latter preferred thinner ones. The theory was that in France, not being muscular is perceived as a sign of belonging to a higher social class whereas having strong arms betrays that you do a physical, low-paid job; whereas in North America, going to the gym seems to be a practice which transcends social class.

EDIT: where as --> whereas